1. Field of the Invention
The present invention relates to a micro-pattern element having a micro-pattern provided on a substrate, such as for a magnetic bubble domain device.
2. Description of the Prior Art
In an element having a micro-pattern, such as for magnetic bubble domain devices, the breakage of a conductor pattern is a serious problem. With reference to FIG. 1, as is well known in the art, a magnetic bubble domain device has a structure in which a garnet film 11 is capable of storing a magnetic bubble, a first insulating film 12, a conductor pattern 13, a second insulating film 14 and a transfer pattern 15 are laminated successively on a non-magnetic substrate 10. (Although the magnetic bubble domain device further comprises a hard bubble controlling film, a detector, and a protecting film, these elements are not shown in FIG. 1 and it must be noted that FIG. 1 is provided for facilitating an understanding of the present invention.) In order to operate the magnetic bubble domain device, it is necessary to generate a magnetic bubble on the garnet film 11 by applying a pulsating current to the conductor pattern 13 or to erase such a magnetic bubble. When the application of pulsating currents is repeated for a long period of time for the generation or erasure of magnetic bubbles, due to current stresses caused by long period application of electric currents the local migration of atoms occurs and discontinuities are formed in the conductor pattern and finally, breakage of the conductor pattern takes place.
This undesirable phenomenon is ordinarily called "electro-migration". Various investigations have been made on the materials of conductors to be used for the formation of conductor patterns so as to prevent the occurrence of this phenomenon. For example, it is known that when Al-Cr or Al-Cu-Cr is employed, the life of the conductor pattern to the point of occurrence of breakage is prolonged and is much longer than the life attainable when Al alone is employed.
However, no satisfactory results can be obtained merely by improvements in the conductor material and it is impossible to completely prevent the occurrence of breakage owing to electro-migration only by improvements in the conductor material. Accordingly, further improvements in other aspects have been desired.